The invention relates to a bucket dredger, and more specifically to a bucket dredger with a swivelling ladder connected to a vessel, a driven upper wheel at the top end and a regular or irregular polygonal lower wheel at the lower end of the ladder, one or more endless chains which are guided along both wheels, and buckets connected to the shackles of these chains.
Such bucket dredgers are known in the art. While in the bucket dredgers of old, the buckets are connected to each other either directly hingingly or through an intermediate shackle, the use of endless chains, to which the buckets are fixed to the shackles thereof, has the advantage that assembly of the whole is simpler and that a bucket can be replaced easily.
Although, naturally, the chains on the wheels are also guided in a lateral direction, this guiding is generally not sufficient for bearing the loads exerted laterally on the buckets without any problems. Because the chains will never be able to be stretched completely taut, a chain will be able to be lifted off the lower wheel when a lateral force is exerted on the bucket, and it then shall not experience sufficient support from its lateral guide. This holds true especially when large volume buckets are to be used.
The bucket dredgers embodied in this fashion are therefore in principle used as elevator dredgers, i.e. the dredging machine is displaced only in the direction of the ladder and not sideways.